The prevalence of destructive interparental conflict and the consequences of such discord for children's adjustment are undeniable. Further, interparental conflict is thought to intensify during infancy and early childhood, putting the emotional and behavioral adjustment of young children particularly at risk. Emotion regulation and adrenocortical functioning have both been linked with exposure to interparental discord and mental health risk, yet little is known about how such conflict may impact the development of maladaptive patterns of coping with negative emotions across early childhood. The current research plan is designed to improve understanding of the associations between interparental conflict, the development of individual patterns of coping with negative emotions, and dynamic emotion regulation profiles that contribute to early mental health risk. Latent class and latent transition analysis will be used to distinguish groups of children with specific patterns of fear and frustration reactivity, regulation strategies, and adrenocortical functioning in response to challenge at 6-, 15-, and 24- months of age. Patterns that are associated with the development of behavior problems in early childhood will be determined. Exposure to interparental conflict will be examined as a predictor of both emotion regulation patterns at each age, and as a predictor of changing patterns of emotion regulation over time. The relationship between class membership and mental health risk at 35-months will also be investigated. Additionally, intensive examination of emotion regulation at the within-person level may provide valuable insight into the processes leading to dysfunctional methods of coping with distress. By modeling how negative reactivity and regulatory strategies affect children's ability to cope with the challenges they face, greater insight can be gained into specific processes that lead to poor adaptation over time. Hidden Markov techniques will be used to model individual emotion regulatory processes in response to challenge at 24-months of age, and groups of individuals with distinct regulatory profiles will be established. Findings from this application could highlight how conflict between parents influences young children's inability to effectively manage their emotions, as well as how this inability contributes to the later development of behavior problems. Further, examining both biological and behavioral aspects of children's management of emotional states over time may inform both researchers and policy advocates on how to best target interventions to address the specific needs of children exposed to interparental conflict and violence.